There are scanning microscopes in which a two-dimensional image of the sample is acquired by scanning the surface of the sample in the X and Y directions with illuminating light using deflecting mirrors or the like. In such scanning microscopes, the size of the observation area on the sample can be altered (i.e., zooming can be performed) without changing the number of pixels (e.g., 512×512) by varying the swinging angles of the deflecting mirrors.